The present invention relates to a continuous paper sheet tearing-off or cutting apparatus of the type provided with a pair of an upper infeed or feed-in roller and a lower infeed or feed-in roller, and another pair of an upper roller and a lower roller rotating at a rotary speed higher than that of the former pair of rollers, so that the difference between the feeding or advancing speeds of the parts of the continuous paper sheet feed through the former roller pair at a low-speed and the latter pair at a high-speed tears off the paper sheet.
According to a first kind of conventional paper tearing-off apparatus mentioned above, the continuous paper sheet is always held or nipped by a pair of an upper feed-in roller and a lower feed-in roller, and another pair of upper and lower high speed rollers. A conventional apparatus of the second kind holds or nips the continuous paper sheet only at the instant of tearing-off by means of both the pairs of rollers. According to a modification of the second conventional apparatus, the pair of the upper and lower feed-in rollers always holds the continuous paper sheet and the another pair of high speed upper and lower rollers nips the sheet only at the instant of the tearing-off operation.
The inventor has improved the conventional continuous paper tearing-off apparatus of the second kind and also the modification of the apparatus.
In general, concerning the conventional continuous paper sheet tearing-off apparatus of the second kind, it is necessary to install a paper sheet transfer apparatus, such as a tractor or the like in the apparatus and the distance between the pair of feed-in rollers and another pair of high speed rollers along the sheet transfer or feeding direction is not changed. The vertical approaching movement of the feed-in rollers and the high speed rollers in order to tear-off a sheet from the continuous paper sheet is set so as to done at the instant or moment that the size of the sheet to be torn-off corresponds to the length of the paper sheet fed through the transfer device, such as a paper drive device or the like.
Disadvantageously, in the conventional apparatus of the second kind, it is necessary to precisely control the separating operation of both the pairs of feed-in rollers and high speed rollers in accordance with the length or volume of the paper sheet fed by the transfer mechanism, and previously to precisely measure the cutting or tearing-off size of the continuous paper sheet in order to fix the timing of the separation. However, it has been difficult to precisely control the separating operation of the pair of the upper and the lower feed-in rollers and the pair of the upper and the lower high speed rollers according to the particular tearing-off size of the paper sheet. In addition, when the thickness of the continuous paper sheet changes, the gaps between the upper rollers and the lower rollers correspondingly increase or decrease, so that it has been difficult to tear-off sheets from the continuous paper sheet at the right or precise position of the sheet, even when the separation of both pairs of rollers is correctly carried out. When the tearing-off size of the sheet torn from the continuous paper sheet is measured and the sheet is set uncorrectly on the sheet measurement mechanism, it is impossible to precisely measure the tearing-off size. If the tearing-off position of the paper sheet is determined according to a wrong measurement result, no precise control of the separation of each pair of rollers is possible and it is not possible tear-off the paper sheet from a correct position.